Four custom specifications by Sophie Kirschner (sophiek@pineapplemachine.com), including example solutions.
The specifications:
BINARY LOGIC: AND, OR, and XOR the two inputs to their respective outputs.
DIGITS: Output hundreds, tens, and ones digits to separate outputs.
ODD OR EVEN: Output 1 if a number is odd, 0 if even. (Modulo 2, essentially.)
LOG BASE 2: Output floor of log base 2 of input.